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Matiashova L, Hoogkamer AL, Timper K. The Role of the Olfactory System in Obesity and Metabolism in Humans: A Systematic Review and Meta-Analysis. Metabolites 2023; 14:16. [PMID: 38248819 PMCID: PMC10821293 DOI: 10.3390/metabo14010016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/16/2023] [Accepted: 12/20/2023] [Indexed: 01/23/2024] Open
Abstract
Obesity, linked to chronic diseases, poses a global health challenge. While the role of the olfactory system in energy homeostasis is well-documented in rodents, its role in metabolism regulation and obesity in humans remains understudied. This review examines the interplay between olfactory function and metabolic alterations in human obesity and the effects of bariatric surgery on olfactory capabilities in humans. Adhering to PRISMA guidelines, a systematic review and meta-analysis was conducted, focusing exclusively on original human studies. From 51 articles, 14 were selected for the meta-analysis. It was found that variations in olfactory receptor genes influence the susceptibility to odors and predisposition to weight gain and poor eating habits. Bariatric surgery, particularly sleeve gastrectomy, shows significant improvements in olfactory function (SMD 2.37, 95% CI [0.96, 3.77], I = 92%, p = 0.001), especially regarding the olfactory threshold (SMD -1.65, 95% CI [-3.03, -0.27], I = 81%, p = 0.02). There is a bidirectional relationship between olfactory function and metabolism in humans. Bariatric surgery improves olfactory perception in obese patients, but it is still unclear if impacting the olfactory system directly affects eating behavior and the energy balance. However, these findings open novel avenues for future studies addressing the olfactory system as a novel target to alter systemic metabolism in humans.
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Affiliation(s)
- Lolita Matiashova
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, 4031 Basel, Switzerland; (A.L.H.); or (K.T.)
| | - Anouk Lisa Hoogkamer
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, 4031 Basel, Switzerland; (A.L.H.); or (K.T.)
| | - Katharina Timper
- Clinic of Endocrinology, Diabetes and Metabolism, University Hospital Basel, 4031 Basel, Switzerland; (A.L.H.); or (K.T.)
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
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Faour M, Magnan C, Gurden H, Martin C. Olfaction in the context of obesity and diabetes: Insights from animal models to humans. Neuropharmacology 2021; 206:108923. [PMID: 34919903 DOI: 10.1016/j.neuropharm.2021.108923] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 12/07/2021] [Accepted: 12/10/2021] [Indexed: 12/12/2022]
Abstract
The olfactory system is at the crossroad between sensory processing and metabolic sensing. In addition to being the center of detection and identification of food odors, it is a sensor for most of the hormones and nutrients responsible for feeding behavior regulation. The consequences of modifications in body homeostasis, nutrient overload and alteration of this brain network in the pathological condition of food-induced obesity and type 2 diabetes are still not elucidated. The aim of this review was first to use both humans and animal studies to report on the current knowledge of the consequences of obesity and type 2 diabetes on odorant threshold and olfactory perception including identification discrimination and memory. We then discuss how olfactory processing can be modified by an alteration of the metabolic homeostasis of the organism and available elements on pharmacological treatments that regulate olfaction. We focus on data within the olfactory system but also on the interactions between the olfactory system and other brain networks impacted by metabolic diseases.
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Affiliation(s)
- Maya Faour
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | | | - Hirac Gurden
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - Claire Martin
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France.
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Berro C, Pendolino AL, Foletto M, Facciolo MC, Maculan P, Prevedello L, Giuntoli DG, Scarpa B, Pavan C, Andrews PJ, Ottaviano G. Olfactory and Gustatory Function before and after Laparoscopic Sleeve Gastrectomy. ACTA ACUST UNITED AC 2021; 57:medicina57090913. [PMID: 34577836 PMCID: PMC8466191 DOI: 10.3390/medicina57090913] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/18/2021] [Accepted: 08/26/2021] [Indexed: 01/09/2023]
Abstract
Background and Objectives: Bariatric surgery is the gold standard for the treatment of morbid obesity, and current evidence suggests that patients undergoing surgery can show changes in their sense of taste and smell. However, no definitive conclusions can be drawn given the heterogeneity of the studies and the contrasting results reported in the literature. Materials and Methods: We enrolled 18 obese patients undergoing laparoscopic sleeve gastrectomy (LSG) and 15 obese controls. At baseline (T0) and 6 months after enrollment/surgery (T1), both groups underwent Sniffin’ Sticks and whole mouth test. Post-operative qualitative taste variations were also analyzed and SNOT-22, VAS for taste and smell, and MMSE were administered. Results: An improvement in the olfactory threshold was observed in the treatment group (p = 0.03) at 6 months. At multivariate analysis, the olfactory threshold differences observed correlated with MMSE (p = 0.03) and T0 gustatory identification (p = 0.01). No changes in sense of taste were observed between the two groups at 6 months, even though nine subjects in the treatment group reported a worsening of taste. This negatively correlated with age (p < 0.001), but a positive marginal correlation was observed with the olfactory threshold difference between T0 and T1 (p = 0.06). Conclusions: Olfaction can improve after LSG, and this seems to be the consequence of an improved olfactory threshold. Although we did not observe any change in gustatory identification, food’s pleasantness worsened after bariatric surgery.
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Affiliation(s)
- Cecilia Berro
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
| | - Alfonso Luca Pendolino
- Department of ENT, Royal National ENT & Eastman Dental Hospitals, London WC1E 6DG, UK;
- Ear Institute, University College London, London WC1X 8EE, UK
- Correspondence:
| | - Mirto Foletto
- Centre for Mechanics of Biological Materials, University of Padova, 35128 Padova, Italy;
- IFSO Bariatric Centre of Excellence, Padova University Hospital, 35128 Padova, Italy;
| | - Maria Cristina Facciolo
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
| | - Pietro Maculan
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padova, 35128 Padova, Italy;
| | - Luca Prevedello
- IFSO Bariatric Centre of Excellence, Padova University Hospital, 35128 Padova, Italy;
| | - Diletta Giulia Giuntoli
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
| | - Bruno Scarpa
- Department of Statistical Sciences and Department of Mathematics Tullio Levi-Civita, University of Padova, 35128 Padova, Italy;
| | - Chiara Pavan
- Department of Psychiatry, University of Padua, 35128 Padua, Italy;
| | - Peter J. Andrews
- Department of ENT, Royal National ENT & Eastman Dental Hospitals, London WC1E 6DG, UK;
- Ear Institute, University College London, London WC1X 8EE, UK
| | - Giancarlo Ottaviano
- Department of Neurosciences, Otolaryngology Section, University of Padova, 35128 Padova, Italy; (C.B.); (M.C.F.); (D.G.G.); (G.O.)
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